The collection includes a line drawing of the Queen by Emin, called HRH Royal Britannia, a drawing of the interior of Westminster Abbey by the sculptor John Maine, and an inkjet print of a drawing which Hockney did on an iPad.

They range in size from Gillian Ayres' Festive I, which is 32 inches (81cm) across, to a four-inch (10cm) wood engraving of the Olympic Stadium by Anne Desmet.

Grayson Perry RA, Design for Kenilworth AM1 (The Royal Collection)

Asked if he had a favourite, Mr Clayton said: "The one that everyone swoons over is the Anish Kapoor because it's so, so beautiful."

He said it was impossible to say how much the collection is worth, though it would run into many millions of pounds.

The collection includes works by 36 painters, 23 sculptors, 19 architects, six engravers, six print makers and one draughtsman.